Wax thread sewing machine



Jan. 12, 1932. E, w 1,840,387

WAX THREAD SEWING MACHINE Filed Nov. 16, 1929 Ei gl i Patented Jan. 12, 1932 UNITED STATES PATENT OFFICE HARRY E. F MASSACHUSETTS, ASSIGNOR TO UNITED SHOE MA- OHINERY CORPORATION, OF PATERSON, NEW JERSEY, A CORPORATION JERSEY OF NEW WAX THREAD SEWING MACHINE Application filed liovember 16, 1929. Serial No. 407,667.

The present invention has relation to wax thread sewing machines such as are used in making shoes, and particularly to machines of this kind employing two threads united in well-known manner to form the familiar lockstitch seam. As commonly contrived, these machines pass a loop formed in one thread through the work by means of the needle, and then pass the supply end of the other thread, carried within a shuttle,

through this loop. The needle thread is put in condition for use by drawing it from its supply through a wax pot in which it is immersed in liquid wax maintained'at a temperature suited to cause thorough impregnation of the thread. Thence it passes to the stitching-point through guides and threadhandling devices which are kept heated to maintain the waxed thread in, supple and slippery condition and prevent its adherence to the parts of the machine with which it makes contact.

The shuttle thread, on the other hand, since it must be passed through the loop of the needle thread s0 as to leave therein a single strand, cannot be handled inthe same manner as the needle-thread, but must be pre-' viously waxed and then wound into a compact mass of small dimensions, to pass bodily through such loop. This previous waxing step makes it necessary and customary to apply heat to the shuttle carrying this wound mass in order to put the shuttle-thread in working condition before it is joined with the warmed and flexible needle-thread.

While effort has been'made to control the temperature of the wax pot so as to keep it above the melting-point and below the burning-point of the wax, no attempt has been made to keep the shuttle-thread heated and conditioned with due regard to the needlethread; the shuttle has simply been heated to make its thread run freely.

I have found that the best results'areattairiedwhenthe degree of heat applied to the shuttle-thread is proportioned to the temperature and consequent condition of the needlei thread at the stitching-point Otherwise, the

is tightened, and the inherent stretch of the threads permits this in spite ot'the attempt to restrain it by means of balanced tensions or thread-clamps. Thus the lock, or point at which the two threads bend around each other, varies its position within the thickness of the work, even being exposed at one surface or the other in objectionable manner in extreme cases.

The present invention has as its main object the provision of means for regulating automatically the degree of heat applied to the needle-thread and to the shuttle-thread respectively, so as to control the condition of one thereof with respect to that of the other, and thus to secure improved and more uniform results in the formation of the seam. A secondary object is to provide means whereby the sewing machine may have its thread-handling parts and its wax pot brought up to operating temperature more quickly than has been possible hitherto.

To these ends, the invention consists in a wax thread sewing machine having in combination, stitch-forming devices including a shuttle, a wax pot, heating means applied to the shuttle and to the wax pot, and means for regulating independently the amount of heat delivered to each. Preferably, the heating means comprises electrical heating units of familiar resistance type, arranged in heattransmitting relation with respect to the wax pot and to the shuttle, and so disposed that the heating of one of such parts may be suspended while the other continues to receive heat, each of these parts being equipped with a thermostat controlling the flow of current to the heating unit or units associated with such part. Preferably also, one or both of the thermostats is adjustable in regard to the temperature at which it may be set to break the flow of current, so that a proper operating balance may be attained between the degree of heat applied to the wax pot and that applied to the shuttle, to put the two threads in the right condition for most favorable cooperation. The heating units may be chosen to produce a degree of heat considerably in excess of that normally needed to keep the parts at proper running temperature, so that though prevented from harmful overheating by the thermostats, they may quickly heat the machine to working temperature and thus avoid the delay commonly resulting after the machines have stood idle overnight when equipped with heating devices adapted to put forth at their maximum only sufficient heat to maintain running conditions.

An illustrative embodiment of the invention in its preferred form is shown in the accompanying drawings in which Fig. 1 is a front elevation of portions of a typicalwax thread shoe sewlng machine with the devices I of the invention applied thereto; Fig. 2 is a front view, and Fig. 3 a plan view of the heating and heat-controlling means which is applied to the machine to condition the shuttle-thread; Fig. 4 is an end elevation of the member containing the heating and heat-regulating devices.

The drawings showthe invention in its preferred form, embodied in a typical Goodyea-r outsole stitching machine for the purpose of illustrating its application, only so much of the machine being shown as is necessary for an understanding of the invention.

This machine is a cnrvedhook needle lockstitch machine for sewing outsoles to the welts of welted shoes. The machine comprises a curved hook needle 2, a looper 4, a loop-spreader 6, a presser-foot 8, a work-support 10, a take-up lever 12, a shuttle 14, a bobbin-case 16 containing the shuttle-thread, and a shuttle race 18, all constructed and arranged to cooperate in forming a lockstitch waxed thread seam. The operating parts of the machine are all driven from a main shaft 20. The parts briefly referred to above in the machine illustrated have substantially thesame constructiomarrangement, and mode of operation as the correspondingparts of the machine illustrated and described in the patent to Z. T. French and W. C; Meyer, No. 473,870, dated April 26, 1892, to which reference may be had for a more complete description. Y I In connection with the machine to which thepresentinventionis applied there is shown a" wax pot for waxing the needle-thread, which is the same in all respects as the wax pot forming the subject-matter of my copending application for U. S. Letters Patent, filed on November v16, 1929, Ser. No. In this wax pot, the bracket 22 is fastened to the column 23 of the machine and is provided with an electric heating unit 24 occupying a chamber within the thickness of the bracket, and connected in series with a thermostat 26 mounted within a cupshaped recess on one side of and integral with the, bracket. "The receptacle 28 for the wax is attached to the other side of the bracket by a dove-tailed tongue-and-groove joint so thatheat will be freely transferred to the receptacle to melt wax put therein, and the interior of the receptacle is void of all heating and heat-controlling devices so that the receptacle can be easily slipped down off the bracket and quickly cleaned and replaced. The thermostat 26 receives adegree of heat from the heating unit 24 that is proportionate to that transmitted to the receptacle 28, and is set to break the electrical circuit supplying the unit when the temperature of the receptacle approaches the burning-point of the wax, and to close the circuit again before the temperature of the wax falls below the point where the thread fails to be thoroughly waxed as it is'drawn from its source of supply through the wax and thence past the tension and take-ups to the needle. Heating means, not shown, are customarily employed to keep hotthe tension,'take-ups, looper, and such other parts as come in contact with the needle-thread, to prevent it from adhering to such parts and to keep it supple and in condition.v p

In accordance with the invention, the shuttle is heated by a heating device controlled in its range of working temperatures by meansindependent of the control means for the wax pot. This heating device is an electric heating unit 30 occupying a chamber 32 in a special heat-transmitting member 34 that also has a cylindrical recess 36 extending into proximity with the chamber 312 and the heating unit 30, within which recess is a thermostat 38 wired in series with the unit 30, the two being supplied with electric current from a suitable source through the leads 40. The member 34 is made of bronze, to transmit heat readily to the shuttle-race 18 and thence to the shuttle 14, to heat the thread, and has its lower surface that is close to the heating unit 30 shaped as indicated at 42 to fit closely against the exterior of the cylindrical shuttle-race. It is mounted upon the shuttle-race by means of a screw 46, passing through the flange 48 of the shuttle-race, and through the bead formed on theshuttle-race, into the metal of the member 34, and by a second screw put through the hole 50 in the 'lower end of member 34 and threaded into the side of the shuttlerace. Acover '52 is applied to close the recess 36 enclosing the thermostat, and to cover the cut-out portion 54for the wiring, being secured in place by screws threaded into the holes 58 formed in the top of member 34. i I The thermostat 38 is of the familiar concavo-convex laminated disctype mounted on a porcelain base 44 with the stud 60 screwthreaded into its supporting plate enabling adjustment of the temperature at which the disc reverses its curvature and breaks the cir cuit through the heating unit 30.

With the arrangement thus described, the heat imparted to the shuttle-thread may be accurately controlled independently of the temperature at which the wax pot and other parts engaging the needle-thread may be operating, and through experiment and adjustment the degree of heat may be found and thereafter automatically maintained which puts the shuttle-thread in the best condition to cooperate with the needle-thread. Also, as before mentioned, this arrangement per- 1 mits the use of large-capacity heating units to bring the machine quickly to operating temperature, without danger of overheating or of disturbing the balanced relation attained between the condition of the needle thread and that of the shuttle-thread.

The invention having been described, what is claimed is:

A wax thread sewing machine having, in combination, stitch-forming devices including a shuttle, a wax-pot, electric heating means for the wax-pot, a thermostat affected by and controlling the temperature of such heating means, electric heating means for the shuttle, a separate thermostat independently affected by and independently controlling the temperature of the shuttle-heating means and cooperating with the first-mentioned thermostat to control the condition of the shuttle thread with respect to the needle :20 thread and means for adjusting one of said thermostats independently of the other to vary the degree of heat attained by the part associated with it to bring the two threads into the desired relative condition. In testimony whereof I have signed my name to this specification.

HARRY E. DOV. 

